1. Field of the Invention
The invention is directed to an adjustable damping valve arrangement for a vibration damper.
2. Background of the Invention
US 2010/252766 A1 shows an adjustable damping valve arrangement with auxiliary valve having an auxiliary valve body comprising two parts. An armature of an electromagnetic actuator is fixed to a central support. Abutting at the front side is a valve seat body which controls a flow cross section of a control space. The pressure on pressure-impinged surfaces at the main stage valve body is adjusted by means of the magnitude of the flow cross section in order to determine the closing forces.
The incident flow in the adjustable damping valve arrangement in this particular arrangement outside the working spaces is always from only one direction regardless of the movement direction of the piston rod, and the damping medium flows out into the compensating space.
However, the damping valve arrangement can also be arranged at the piston rod, in which case the flow through the damping valve arrangement is in two directions. Particularly in this variant, it may happen over a prolonged deenergized state of the actuator, e.g., in case of failure of the power supply, that the main stage valve is permanently open to an extent which is not acceptable for driving safety.
It is an object of the present invention to overcome the problem of the main stage valve being opened in an undefined manner during outage of the power supply.